• 한국환경과학회지
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• 제25권2호
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• pp.191-216
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• 2016

Since prolonged exposure to elevated ozone ($O_3$) concentrations is known to be harmful to human health, appropriate control strategies for ozone are needed for the non-attainment area such as Seoul, Korea. The goal of this research is to assess factors linked with the 1-hour ozone exceedance through a decision tree model. Since ozone is a secondary pollutant, lag times between ozone and explanatory variables for ozone formation are taken into account in the model to improve the accuracy of the simulation. Results show that while ozone concentrations of the previous day and $NO_2$ concentrations in the morning are major drivers for ozone exceedances in the early afternoon, meteorology plays more important role for ozone exceedances in the late afternoon. Results also show that a selection of lag times between ozone and explanatory variables affect the accuracy of predicting 1-hour ozone exceedances. The result analyzed in this study can be used for developing control strategies of ozone in Seoul, Korea.

• 한국군사과학기술학회지
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• 제12권2호
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• pp.248-257
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• 2009

The aim of this paper is to propose fighter aircraft's mission severity model which can be used as one of key factors for designing a structure and determining design life of KF-X. The mission severity is a quantitative data of flight loads and expressed by Nz(Vertical Load Factor) exceedances or occurrences. The severities of the flight loads depended on the circumstances of the countries which operate fighter aircraft. In this paper we have studied on Nz occurrences/exceedances of ROKAF fighter aircraft to generate mission severity model for the KF-X. The analyses of flight data were accomplished by using the Matlab.

• Journal of Korean Society for Atmospheric Environment
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• 제15권E호
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• pp.45-54
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• 1999

The effectiveness of NOx emission reductions from power plants to alleviate persistent ozone nonattainment in the esterm Unites States was investigated with a focus on the Northeast Corridor, centered on New York City. The 1995 ozone episode along with the 2007 base case emission scenario was used with the Variable-Grid Urban Airshed Model(UAM-V) to determine ozone concentrations. Several scenarios based on EPA's proposal issued on October 10, 1997 were examined. Although it is widely recognized that the eastern United States includes a large Nox-sensitive region(e.g., Sillman, 1999), the study revealed that reducing NOx emissions from power plants beyond 500 miles (800km) was not effective for reducing ozone exceedances in the region. It was also found that NOx emissions from power plants play an important role in local ozone exceedances.

• 한국환경과학회지
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• 제27권7호
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• pp.587-595
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• 2018

This research investigated the characteristics of NO and $NO_2$ concentration at roadside (Choryangdong) and residential (Sujeongdong) locations in Busan. The NO concentration at roadside and residential were 34.7 and 8.0 ppb, respectively, and $NO_2$ at roadside and residential were 31.6 and $18.0ppb\;{\mu}g/m^3$, respectively. The NO concentration was the highest in winter at roadside at 37.1 ppb, followed by 35.0 ppb and 34.0 ppb in summer and fall, respectively. $NO_2$ concentration was the highest in spring at roadside at 39.6 ppb, followed by 30.4 ppb and 28.3 ppb in fall and winter, respectively. Number of exceedances per year of 1 hr limit value (0.10 ppm) for $NO_2$ at roadside and residential were 3,585 and 3 hours, respectively. Number of exceedances per year of 24 hr limit value (0.06 ppm) for $NO_2$ at roadside and residential were 32 and 1 days, respectively. Number of exceedances per year of 1 hr limit value (0.1 ppm) for $O_3$ at roadside and residential were 1 and 14 days, respectively. These results indicated that understanding the relationship between roadside and residential could provide insight into establishing a strategy to control urban air quality.

• 한국대기환경학회지
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• 제30권5호
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• pp.504-509
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• 2014

Twenty-five stations of the urban monitoring network in Seoul were assessed with a focus on surveillance function of the exceedances of 8-hour ozone and 24-hour $PM_{10}$ standards. The two standards were selected because their attainment rates were particularly low. Two hierarchical cluster analyses were performed to group stations with similar atmospheric environments-one using daily highest 8-hour [$O_3+NO_2$], 8-hour $O_3$ concentrations plus corresponding 8-hour $NO_2$ concentrations considering the interconversion of $O_3$ and $NO_2$, and the other using 24-hour $PM_{10}$ concentrations. An index to measure higher concentration and exceedances of the standards was introduced. Within a cluster, sufficiently high score was assigned to the trends station or the station with higher index. Scores for $O_3+NO_2$ and $PM_{10}$ of a given station were added and ranked in the descending order to determine the relative importance.

• 한국수자원학회논문집
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• 제41권5호
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• pp.527-544
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• 2008

GPD 모형은 수문학 극치확률량 해석에 주로 적용되어 왔다. 극치 통계의 주목적은 드문 사상의 예측이며, 주요 문제점으로는 임계값 또는 임계값 초과치들에 대한 정확한 산정방법이 없어 그 추정이 매우 어렵다는 것이다. 본 연구에서는 임계값 또는 임계값 초과치들을 산정하기 위하여 4가지 방법을 적용하였다. 그 비교를 위하여 GPD 모형에 적용하여 7개의 지속시간(1, 2, 3, 6, 12, 18 및 24시간)과 10개의 재현기간(2, 3, 5, 10, 20, 30, 50, 70, 80 및 100년)에 대한 매개변수 및 Quantile을 추정하였다. 3변수 GPD의 매개변수 및 Quantile을 추정하기 위하여 MOM, ML과 PWM을 적용하였다. 적합도를 추정하기 위하여 K-S, CVM 및 A-D 검정을 수행하였고 Monte Carlo 실험으로 상대 제곱근오차를 산정하였다. 이러한 방법들을 이용하여 임계값 산정방법들을 비교하여 최적화된 방법을 추정하였다.

• 한국대기환경학회지
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• 제13권1호
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• pp.41-49
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• 1997

Status of photochemical air pollution in the Greater Seoul Area (GSA) between 1990 and 1995 was assessed in terms of frequency distributions, number of days exceeding standards, average concentration and meteorological effects. In Seoul compared with other areas in Korea, daily maximum concentration was higher but average concentration was not so high due to lower daily minimum from April to October. The top 5th percentile was high especially in summer season. Average number of days exceeding 100 ppb at monitoring stations in GSA was highest in 1994, the hottest year, but it was only 4 days a year. Mean meteorological pattern of high ozone days could be summarized as low wind speeds, high temperatures, strong solar radiation, and low precipitation. Westerlies were more frequent on high ozone days and at Pangi station located in the eastside of GSA, both number of high ozone days and average concentration were high. Effect of precursor transport on the rise of ozone concentration was, however, not consistently important on the whole in GSA.

• 한국대기환경학회지
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• 제15권2호
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• pp.139-150
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• 1999

The ozone concentrations measured at the National Air Monitoring Stations between 1990 and 1995 were reviewed to detect any anomalies in the measurements. By screening the cases, in which variation of the ozone concentration from the previous measured value is greater than 75ppb, 125 station-days were identified as the test cases for the anomaly test. Historical and parallel consistencies of the measured concentrations were examined by plotting data for each test case. The detected anomalies can be classified into four categories; single outliers, anomalous variations during the startup period, baseline rises, and fluctuations in th diurnal variations. Anomalies were detected in as many as 80 cases among 125 test cases. Because of these anomalies, the number of hours exceeding 100ppb in the areas other than the Greater Seoul Area(GSA) could decrease from 157 to 107. Further studies for developing the methodology for eliminating the abnormal monitoring data are warranted for the data from the National Air Monitoring Stations are official to the both inside and outside of the country.

• 한국환경보건학회:학술대회논문집
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• 한국환경보건학회 2003년도 Challenges and Achievements in Environmental Health
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• pp.66-75
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• 2003

This paper reviewed available information/data compiled by various agencies, institutions, and experts, including the academe. The review concentrated on five of the most pressing problems such as air pollution, water pollution, land pollution related to the problem of solid wastes, toxic and hazardous chemical wastes and deforestation. Most of the data presented focused on Metro Manila. Past air monitoring data showed significant exceedances of national air quality guideline values especially for particulates and lead. Many of the country's rivers and lakes have deteriorated, some were declared biologically dead. The acute solid waste problem and the proliferation of toxic and hazardous chemicals have led to the enactment of legislation. Uncontrolled deforestation has taken its toll on the environment and people. Various actions were undertaken by the national administration with the cooperation of other sectors to address environmental problems. However, constraints to the enforcement of environmental laws and programs must be minimized to attain the desired level of environmental protection and management.

• 응용통계연구
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• 제27권4호
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• pp.655-665
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• 2014

폭염, 폭우와 가뭄 등과 같은 이상 기후 현상에 대한 적절한 대응이 최근 많이 요구되고 있다. 이상 기후 현상을 분석하기 위해 극단값 분석 기법을 적용할 수 있는데, 본 논문은에서는 한국의 여름철 강수량 자료(1973년부터 2012년까지의 5월부터 9월)를 분계점 초과값 모형으로 분석해보았다. 분계점은 한국의 기상관측소들을 5개의 군집으로 나누어, 각 군집별로 지리 정보와 시간을 공변량으로 하는 분위수 회귀 방법을 통하여 추정하였다. Northrop과 Jonathan (2011)과 같이 극단값들이 시공간적으로 독립이라고 가정하고 분석한 후, 추정오차와 검정 과정에 공간 종속성을 반영하였다.